In a variety of commercial and industrial settings, it is necessary to remove one or more components from a fluid, i.e., a gas or a liquid, before the fluid can be used for a particular purpose. For example, before contaminated water can be drunk, any chemical contaminants must be removed. Likewise, before compressed air can be used, for example to drive power tools, any water or water vapor must be removed or the tools will rust.
Many types of devices are available to remove one or more components from a fluid. On particularly effective class of devices characteristically comprises an apparatus which directs a flow of the fluid through a sorbent material, i.e., a material which sorbs certain components. The sorbent material is typically in the form of a bed of sorbent particles which may be either loosely loaded or loaded under compression into a vertically oriented vessel. During a sorbing phase, the fluid containing the components is pumped at a certain pressure into either the top or the bottom of the vessel and then passed through the sorbent particle bed where the components are sorbed by the sorbent material. The fluid, now free of the components, is then removed from the other end of the vessel.
To extend the useful life of these sorbing apparatus, the sorbent bed is periodically regenerated, i.e., stripped or the components it has sorbed from the fluid. During a regenerating phase, the vessel is typically depressurized. Then, a heated and/or component-free fluid is flushed through the sorbent bed, purging the component from the sorbent particles. This purging fluid, now containing much of the components previously sorbed by the sorbent bed, is then exhausted. Once the sorbent bed is sufficiently free of the components, the vessel is repressurized and the fluid containing the components is again pumped through the vessel. The regenerated sorbent bed then continues sorbing the components from the fluid. The sorbing apparatus can continue cycling between the sorbing phase and the regenerating phase for an extended period.
As effective as these apparatus are, they nevertheless have several undesirable characteristics. For example, they frequently generate significant quantities of sorbent dust, i.e., small fragments of the sorbent particles. Sorbent dust, which is extremely abrasive, can flow with the fluid through the end of the vessel. To withstand the destructive effect of this abrasive dust, any downstream pipes and valves are typically made of a heavier gauge than would otherwise be necessary and/or are specially designed to accommodate the severe conditions. Such pipes and valves significantly increase the weight and cost of the apparatus. These sorbing apparatus typically include a sorbent dust filter downstream from the sorbent bed to prevent migration of the sorbent dust. While the sorbent dust filter may collect much of the dust, it nonetheless adds to the mechanical complexity of the apparatus. It also increases both maintenance and operational costs since the filter must be periodically cleaned or replaced.
Sorbent dust may be generated in a variety of ways. For example, sorbent particles as received from the manufacturer frequently include a significant amount of sorbent dust generated during the manufacturing process and during shipping. Further, when loading the sorbent particles into the vessel, the particles can abrade against one another, generating the dust. They can also abrade against one another whenever the sorbent bed is jarred, e.g., when the sorbing apparatus is transported, or when it must be mounted where it is subjected to vibration, e.g., on board a ship. Further, once loaded, the sorbent particles at the bottom of the bed bear the weight of the entire sorbent bed and may be crushed into sorbent dust by the load. To avoid fragmenting or crushing sorbent particles, these sorbing apparatus characteristically use extremely hard particles which significantly limits the type of sorbent that can be used.
Sorbent dust may also be generated if the sorbent bed becomes fluidized, i.e., if the particles of sorbent are moved by the fluid passing through the bed. The moving sorbent particles may collide with and/or abrade against one another, generating the dust. The avoid fluidization in the sorbing phase, available sorbing apparatus maintain the velocity of the fluid at a very low level which, for some applications, significantly limits the amount of fluid that can be processed in a given amount of time. To avoid fluidization during the regenerating phase, the sorbing apparatus typically not only maintain the velocity of the purging fluid at a very low level but also depressurize and repressurize the vessel relatively slowly. For a given cycle time, this significantly decreases the amount of time available for flushing the sorbent particles during the regenerating phase. Known sorbing apparatus also avoid fluidization by comprising the sorbent bend, e.g., by using spring-loaded mechanisms which bear against the top of the bed. Not only are these mechanisms frequently heavy and expensive but they further add to the load that the particles at the bottom of the bed must bear.
Another undesirable characteristic of known sorbing apparatus is that the sorbent bed, although initially loaded evenly, may develop channels since the sorbent particles may settle within the bed due to vibration or shock. These channels allow the fluid to bypass the sorbent particles and decrease the effectiveness of the sorbent bed in removing the components from the fluid. To minimize channelling, the vessels of known sorbing apparatus are generally oriented vertically. Vertical vessels, however, require supports, such as legs, to keep them upright. These supports, again, significantly increase both the weight and cost of the apparatus. Further, it is frequently desirable that these devices be portable. Since the center of gravity of a vertical vessel is much higher than that of a horizontal, the apparatus is more likely to tip over when moved.